>>
>>Hi Viv,
>>The problem seems to be with silverlight runtime as I can still work on my silverlight 3 projects but when I try to start debugging to run them I get an error and it bails out. I now have to start without debugging. The only difference is when Silverlight 4 (not the tools or SDK) got installed it replaced the Silverlight 3 runtime.
>>It sounds like you are able to run with debugging for both 3 & 4 so when you look in the control panel under programs & features, what version of Silverlight runtime do you have?
>
>Hi,
>Mine's on an old XP Pro laptop. The listing above is taken from the Control Panel 'Add or Remove Programs' window. And, as above, apart from the first four components listed there's also an entry which just says 'Microsoft Silverlight' - it's only 1.29Mb so I assume that's the runtime? The version number is the same as for the Silverlight 4 SDK (I see I mis-typed a digit in the previous post)

OK, well then it looks like you have only the version 4 runtime installed and yet can run Silverlight 3 applications in debugging so my problem must be related to some other reason.
Thanks, I guess I will do some more experimenting. Not quite ready to just move everything to Silverlight 4 as I don't think the SDK is officially released yet.
Thanks
Tim